Electric door operator

ABSTRACT

907,388. Control of A.C. motors. KAWNEER CO. Dec. 22, 1959 [Jan. 2, 1959], No. 43577/59. Class 38 (3). [Also in Group XXV] An electrically powered door operating appliance comprises a servomechanism for driving the door between closed and open terminal positions, the servomechanism including a servomotor supplied with a drive voltage derived by comparing a reference voltage representing the position to which the door is to be moved with a varying feedback voltage developed by a feedback means driven simultaneously with the door. The door 34, see Fig. 2, has an upper pivot 36 driven through a gear assembly 46 by an electric servomotor 44, the drive voltage for which is derived from a potentiometer network 47 which is unbalanced in response to the passage of a person over a treadle mat 42 and is rebalanced by a feedback device 50 comprising a variable transformer 94 controlled by a cam 110 secured to a shaft 76 in the gear assembly. Servomotor.-The servomotor 44 is a twophase squirrel-cage induction motor, the rotor of which rotates in response to a rotating magnetic field produced by two separate field windings, a reference winding 60 continuously energized from an A.C. source 63 and a control winding 48 energized by a voltage differing in phase by 90 degrees supplied by the unbalanced potentiometer network 47. The motor also includes a damping winding 56 energized by a constant voltage D.C. controlled by a pair of switches 170, 174 operated in response to the position of the door by a cam 180. The D.C. is derived from a conventional rectifier type circuit 58 (Fig. 8) connected in parallel with the primary winding 91 of the transformer 90 (see below) and comprising a resistance 126, rectifiers 123, 124 and a capacitance 128. An inductance 186 is serially connected with the damping winding 56 to counteract the effect of the capacitance 128. Potentiometer network.-The network 47 (Fig. 4) comprises a first branch 92 formed by the secondary winding of a step-up transformer 90 connected to the A.C. source 63 and a second branch formed by the variable transformer 94. The centre arm 96 comprises the primary winding 98 of a step-up transformer which supplies the drive voltage to the control winding 48 of the motor, one end 96a of the arm being connected by a switch 97 in response to actuation of the treadle mat 42 to one of two voltage levels 100, 104 on the winding 92 and the other end 96b being connected to a slider 99 movable along the winding 94. Feedback device.-The slider 99 is moved through a rack-and pinion connection 118, 120 by a bar 116 carrying a follower 114 engaging the cam groove 112 of the cam 110. When the door is closed and set to open to the left the follower is located at 137 (Fig. 3) and the slider 99 is at the voltage level 102 which is equal to voltage level 100. When the switch 97 moves to voltage level 104 in response to actuation of the treadle mat the unbalanced network provides a drive voltage for the motor and during the first 2¢ degrees of door movement the follower 114 moves along the portion 132 of the cam groove to the end of the portion 133 and the slider moves to voltage level 105. From the 2¢ degrees to 87¢ degrees position of the door, the follower travels along the portion 133 and the slider voltage remains constant, while during the last 2¢ degrees of opening movement the slider travels in the portion 134 and the slider moves to voltage 106 which is equal to voltage 104. During closing movement of the door the follower moves back to the point 137. If the door is moved accidentally from its closed position, e.g. by wind pressure, the follower moves in the portion 132, 131 towards the portions 133 or 130 and the slider moves towards voltages 105 or 101, respectively, thus providing a drive voltage to the motor so that the latter exerts an appropriate restoring force on the door. Motor interrupting sub-circuit. This operates to open-circuit the motor control winding 48 for a predetermined time interval (about threetenths of a second) and simultaneously energizes the damping winding 56 which thereby becomes quickly effective. The sub-circuit comprises a time pulse relay 190 (Figs. 7, 8), the coil 190a of which, when energized, opens a switch 192 in the circuit of the centre arm 96 of the potentiometer network and closes a switch 194 between the damping winding and the D.C. connection 144. The sub-circuit is set when both the terminals 176 and 172 of switches 174, 170, respectively, are closed, i.e. when the door is between its 30 degrees and 60 degrees open positions, and the D.C. voltage 144 is applied to both plates of a condenser 200. When either pair of contacts 172, 176 is opened, the voltage 144 is removed from the condenser plate 200b and a charging current flows through the winding 190a, energizing the latter. The sub-circuit is reset when the contacts are closed, the condenser discharging through a rectifier 196 and resistance 198. Control circuit; normal door operation.-The door operating appliance is intended during normal operation to open the door automatically when a person steps on to the approach side 42a of the treadle mat and to close the door after the person has left the exit side 42b. It also exerts a restoring torque (see above) when the door is moved accidentally from its closed position, e.g. by wind pressure, and prevents the door from opening automatically if a person is standing on the exit side 42b of the mat, thus avoiding the risk of injury. It also permits panic opening of the door in the opposite direction, and subsequently resets the door for normal automatic operation. Fig. 8 shows the condition of the control circuit when the door is closed, the motor control winding 48 being de-energized and the damping winding 56 being energized from the connection 144 of the D.C. circuit 58 through conductor 181, resistance 182, contacts 175 of switch 174, socket 165, plug 167, conductor 187, switch 162, inductance 186, the winding 56, and conductor 237 to earth. A person stepping on to the approach side 42a of the treadle mat closes a switch 80 which energizes an operating relay 140, powered from a short portion 143 of the secondary 92, to close switch 149 and complete the energizing circuit for a control relay 160 from the terminal 144, resistance 153, switch 149, switch 154, relay winding 160a, to earth. The control relay operates switch 97, which moves from voltage 100 to voltage 104 and unbalances the network 47 to provide the drive voltage to the motor the feedback device operating as described above to rebalance the network as the door opens. The control relay also de-energizes the damping winding by opening the switch 162, closes switch 164 which connects the damping winding to the switch 170, and closes switch 166, in parallel with switch 154. When the door reaches its 30 degrees open position the cam 180 operates switch 174 to close the contacts 176 and set the motor interrupting sub-circuit. On reaching the 60 degrees open position the switch 170 is operated, the opening of contacts 172 causing operation of the interrupting subcircuit and consequent interruption of the motor for a short duration, and the closing of contacts 171 completing a circuit for the damping winding from the connection 144 through conductor 181, resistance 182, contacts 171, socket 165, plug 167, conductor 184, switch 164, inductance 186, the winding 56 to earth. The door then moves from the 60 degrees to 90 degrees position under the influence of both the damping winding 56 and the control winding 48. When the person steps from the entrance side 42a to the exit side 42b of the treadle mat, whether or not the door is by then fully open, the switch 80 is opened, thereby de-energizing the operating relay 140, and a switch 82 is closed to energize a safety relay 150. If a short time interval occurs between the opening of switch 80 and the closing of switch 82, the control relay 160 is maintained energized by the discharge, through the winding 160a, of a condenser 173. The operation of the safety relay closes switch 152 to complete a second energizing circuit for the control relay 160, so that the door is held open so long as the person remains on the mat exit side 42b. When the person steps off the mat the safety relay is de-energized, the switch 152 opens and the control relay is de-energized so that the switch 97 returns to the voltage 100, thus unbalancing the potentiometer network, the switch 162 closes, thus connecting the switch 174 with the damping winding 56, and the switch 164 opens, thus disconnecting the switch 170 from the damping winding. The closing. movement of the door corresponds exactly to the opening movement just described, the interrupting sub-circuit being set at the 60 degrees open position and operated at the 30 degrees open position, to prevent the door from swinging violently should a person step on to the entrance side 42a of the mat during the predetermined time interval. Safety operation.-The door is prevented from opening if an inattentive person is standing on the mat exit side 42b. If this happens, the switch 82 is closed to energize the safety relay 150 which opens switch 154 so that the operating circuit for the control relay 160 through the switch 149 is opened. The door closing movement is also arrested should a person step on to the mat exit side 42b, for during normal closing movement the relays 140, 150 and 160 are all de-energized, and should the switch 82 be closed the safety relay is energized to close the switches 152 and 158 and open the switches 154 and 156. The opening of switch 156 opens the circuit between the primary winding 98 and the voltage 100 and thus de-energizes the control winding 48, while the closure of switch 158 completes an energization circuit for the damping winding 56. The door remains stationary even if another person steps on to the mat entrance side 42a since the operating circu

June 19, 1962 w. G. HEINSMAN ETAL 3,039,764

' ELECTRIC DOOR OPERATOR Filed Jan. 2, 1959 7 Sheets-Sheet 1 a K E 28 M E mum! INVENTOR. WILLIAM G.HEINSMAN, JACK M. ROEHM AND BY HERBERT $.WILLE ATTORNEYS June 19, 1962 Filed Jan. 2, 1959 W. G. HEINSMAN ET AL ELECTRIC DOOR OPERATOR 7 Sheets-Sheet 2 INVENTORS W\LL\AM G- HE\NSMAN JACK M. ROEHM AND BY HERBERT 5. WILLE ATTORA/EiG June 19, 1962 w. G. HEINSMAN ETAL 3,039,764

ELECTRIC DOOR OPERATOR Filed Jan. 2, 1959 7 Sheets-Sheet 3 DAMFHNG SUB CIRCUIT 52 K a I //Z 1 U 7 MOTOR INTERRUPTING SUB ClRCUlT 54 CONTROL RELAY I60 TO EN) /74 'ro TRANS- FORMER 98 INVENTORS WILLIAM G. HENSMAN JACK M. ROEHM AND HERBERT S. WlLLE Arron/5V5 June 19, 1962 w. s. HEINSMAN ETAL 3,039,764

ELECTRIC DOOR OPERATOR Filed Jan. 2, 1959 7 Sheets-Sheet 4 242 24 4 300 x304 ESL'TQ QG E' 774, 24?";

INVENTORS:

WlLLlAM G. HE\NSMAN JACK M. ROEHM AND BY HERBERT S. \N\\ \..E

AT TORA/E Vs CONTROL RELAY 356"? w. G. HEINSMAN ET AL 3,039,764

ELECTRIC DOOR OPERATOR '7 Sheets-Sheet 5 June 19, 1962 Filed Jan. 2, 1959 June 19, 1962 w. G. HEINSMAN ET AL 3,039,764

ELECTRIC DOOR OPERATOR Filed Jan. 2, 1959 7 Sheets-Sheet 6 792 [a AUTOMATIC OPERATION 5' {CONTROL W/IVD/IVG'I /04 (AIAUTOMATIC OPEN/NO IBIAUTOMATIC CLOSING 2m 971 48% m4 sub: 700 HIJIHH I-HTT HHU I06 /05 /02 99 /05 90 OPEN H GLOSED POSITION I00 43g 00 02 7 60 ar leo 90 8%" 30 z o mus 2P2 II AUTOMATIC OPERATION (DAMP/N6 W/ND/A/G} (AIAUTOMAT/C opewma IBIAUTOMAT/G CLOSING 90 OPEN POSITION 0 60 90' so 30 0' TIME 17; J2 ALL OPERATIONS (SL IOE R VOLTAGE) A 5 AUTOMATIC OPEN/NO 8 CLOSING 02 872 90 7 PANIC OPERATION fighzfi (CONTROL WINOINGI I IGIMANUAL aPEN/NG l0) AUTOMATIC CLOSING PERSON PUSHES PERSON STEPS man 5 a flask-s 2 wzx'ixzz? h 7 /04 2 masons/Epsom H HHHH HHHHHHHTHHHWMZ MAT ENTR. 5105 J r /O/ L99 TIME 010350 40 8 30 0 0 PANIC OPERATION Z 3 14 (DAMP/N6 WINDING) )MANUAiOPEN/NG ID} A UTOMA TIC CLOSING I I INVENTORS WILLIAM smsmsmm,

JACK M. ROEHM AND A /5 TIME BY HERBERT S. WILLE 27" ZZ AOVI, Koeflzw -wen, $0 aflzfl uzn am? 744 44, O ATTORNEYS June 19, 1962 w. G. HEINSMAN ETAL 3,039,764

ELECTRIC DOOR OPERATOR Filed Jan. 2. 1959 '7 Sheets-Sheet '7 jcz'g lfi CLOSER OPERATION (CONTROL WIND/N6) (A/MAIVUAL (B/AUTOMATIO (OMIANUAL {DIAUTOMAT/O OPENING CLOSING OPEN/N6 CLOSING 5553 5,, PERSONPUSHES pznsow RELEASES PERSON SIDE) SIDE mum/1Q??? PE v 2/0001? i z fgga'z-gg hff figggowRELEAsEs llllllllllllllllllllliMIN lo? /02 am 0mm nmm m mumnn m POSITION /0/ 0 so so 2 0 02 80 3o2 0 2 TIME 2 2 5 CLOSER OPERATION 5* (DAMPER wwom/a) IAIMANUAL (BIAUTOMAT/O IOIMANUAL roMuromr/a Oljf'N/NG CLOSING OPEN/N6 CLOSING OOLOSED POSITION I 0 a0 a0 a0 a 0 30 so 3o 0 r 00... NH"

IN V EN TORS WILLIAM G. HEINSMAN, BY JACK M. ROEHM AND HERBERT $.WILLE ATTORNE Y5 United States Patent 3,039,764 ELEGTRIC DOOR OPERATOR William G. Heinsman, Chicago, Ill., and Jack M. Roehm and Herbert S. Wille, Niles, Mich., assignors to Kawneer Company, Niles, Mich a corporation of Delaware Filed Jan. 2, 1959, Ser. No. 784,673 49 Claims. (Cl. 268-33) The present invention relates to electric door operators and, more particularly, to an improved single-acting operator for positively controlling the opening and closing movements of a door.

It is an object of the present invention to provide a new and improved electric door operator for automatically opening and closing a door and for positively controlling the movement of the door during its opening and closing.

It is another object of the present invention to provide an electric door operator which has excellent performance characteristics and is safe and dependable in operation.

It is yet'another object of the present invention to provide an electric door operator for initially opening and closing a door at an optimum speed and for moving the door adjacent both its open and closed speed at a slower latching speed.

It is another object in accordance with the previous object to rapidly change the speed of the door from its optimum speed to its latching speed.

It is another object of the present invention to provide an electric door operator embodying a positional servomechanism for developing a door moving torque having an initially high value for overcoming the inertia of the door, an intermediate constant value for driving the door at an optimum speed throughout substantially the entire movement of the door, and a final value decreasing to zero to provide for a gradual reduction of the driving force of the motor.

It is still a further object of the present invention to provide an electric door operator disposed substantially within a transom element of a doorway frame.

It is another object of the present invention to locate the mechanical components of an electric door operator within a transom element of a doorway construction and the electrical circuilt of the operator within the transom element and door jambs of the doorway construction.

It is a further object of the present invention to provide an electric door operator for automatically returning a door to its open or closed position incident to manual displacement of the door in either direction away from either its open or closed position.

It is still a further object of the present invention to provide an electric door operator which is adapted to be set to automatically open and close a door on a selected side of a doorway.

It is another object of the present invention to provide an electric door operator which positively controls the opening and closing movement of a door on one side of a door frame yet which permits panic or manual opening of the door on the other side of the door frame.

3,039,764 Patented June 19, I962 "ice in either its open or closed position a positive rotative torque for opposing in and out wind pressure.

It is a further object in accordance with the previous object to provide a rotative torque which is proportional to door displacement and reaches a maximum value before the door rail leaves the door jamb.

It is still a further object of the present invention to provide an electric door operator that immediately arrests the closing movement of the door when a person stands adjacent to the exit side of the doorway.

Other objects and advantages of the present invention will become apparent from the following description of illustrative embodiments thereof, in the course of which reference is had to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a door and doorway con struction provided with an electric door operator embodying the features of the present invention for automatically opening and closing the door;

FIG. 2 is a partially schematic, partially diagrammatic, oversimplified view illustrating certain features of the electric door operator of FIG. 1, and showing particularly the positional servomechanism;

FIG. 3 is a fragmentary top plan view of a follower de-, vice embodied in the electric door operator of FIG. 1;

FIG. 4 is a schematic circuit diagram of a potentiometer network embodied in the electric door operator of FIG. 1;

FIG. 5 is a schematic circuit diagram of a modification of the potentiometer network of FIG. 4;

FIG. 6 is a schematic circuit diagram of yet another modification of the potentiometer network of FIG. 4;

FIG. 7 a schematic diagram of a damping subcircuit and a motor interrupting subcircuit embodied in the schematic circuit diagram of FIG. 2;

FIG. 8 is a detailed schematic circuit diagram of the electric door operator of FIG. 1;

FIG. 9 is a diagrammatic top plan view of the doorway construction and door of FIG. 1 illustrating various movements of the door relative to the doorway;

FIG. 10 is a diagram illustrating the magnitude of the voltage existing at various points in the potentiometer network of FIG. 4 and the relative magnitude of voltage applied to a control winding of a servomotor during auto matic operation of the door operator of FIG. 1;

FIG. 11 is a diagram illustrating the magnitude of volt- 1 age applied to a damping winding of the servomotor It is a further object of the present invention in accordance with the previous object to provide an operator which automatically returns the door to its closed position after panic or manual opening of the door and which thereafter is able to automatically open and close the door without manual attention.

It is another object of the present invention to provide an automatic door operator which is adapted to be conditioned to operate as a double-acting door closer.

It is another object of the present invention to provide an electric door operator which develop-s when the door is during automatic operation of the operator;

FIG. 12 is a diagram of the magnitude of the slider voltage in the potentiometer network of FIG. 4;

FIG. 13 is a diagram illustrating the magnitude of voltage applied to the control Winding of the servomotor when the operator is panic or manually operated;

FIG. 14 is a diagram illustrating the magnitude of voltage applied to the damping winding of the servomotor when the operator is panicked or manually operated;

FIG. 15 is a diagram illustrating the magnitude of voltage applied to the control winding of the servomotor when the operator functions as a double-acting door closer;

FIG. 16 is a diagram illustrating the magnitude of voltage applied to the damping Winding of the servomotor when the operator functions as a double-acting door closer; and

FIG. 17 is a fragmentary elevational view of a component of the control circuit used to control the magnitude of the voltage applied to the control Winding during panic operation of the door.

Briefly, the electric door operator embodying the principles of the present invention functions automatically to open and close a door on one side of a doorway in response to movement of one way traffic through the doorway. It positively controls the speed of the door and provides a normal opening or closing speed throughout most of the movement of the door and then a latching speed adjacent to the door open or closed position. The operator permits panic or manual opening of the door on the other side of the doorway and thereafter automatically returns the door to its closed position, the operator being able to automatically open and close the door without resetting or repairing any panic devices. The door may also be automatically held in its open position on one side of the doorway for an indefinite period of time. In addition, the operator is adapted to function as a double-acting door closer to automatically return the door to its closed position after the door has been manually opened on either side of the doorway. The electrical and mechanical components of the electric door operator are disposed within the doorway construction and are not visible on either side of the construction, whereby a modern appearing entrance is provided.

The operator comprises a positional servomechanism which is either holding a null position or seeking a null position. The servomechanism is controlled by an electrical control system including a treadle mat subcircuit, a damping subcircuit and a motor interrupting subcircuit. An electric servomotor of the servomechanism is in driving engagement through a gear assembly with a door spindle mechanically connected to the door and includes a control winding energized by a potentiometer network. When a person actuates the treadle mat subcircuit, the potentiometer network is unbalanced to provide for the motor control winding a driving voltage Which causes the door to move to its open position and the servomechanism to seek a door open null position. The servomechanism further embodies a mechanical follower or feedback device for rebalancing the potentiometer network and controlling the magnitude of the driving voltage supplied to the motor control winding. Specifically, the network de Velops a driving voltage havin an initially high magnitude to overcome the inertia of the door, a lower substantially constant magnitude to move the door at an optimum speed, and a magnitude decreasing to zero to provide for a gradual reduction in the driving force of the motor. After a person has passed through the doorway, the treadle mat circuit is deactuated to again unbalance the network to provide a driving voltage for the motor control winding thereby to cause the servomechanism to seek a door closed null position.

The door during either its opening or closing movement first moves at a normal optimum speed but during its last 30 degrees of movement travels at a reduced latching speed. When the door begins to move into its last 30 degrees of travel, door position-sensitive switches are closed to operate the damping subcircuit throughout the 30 degrees of latching movement and simultaneously to operate the motor interrupting subcircuit for a few degrees of movement. The damping subcircuit effects the energization of a damping winding in the servomotor to develop a resistive force having a magnitude proportional to the speed of the motor. The motor interrupting subcircuit causes the motor control winding to be open circuited for a predetermined time interval to permit the motor to be abruptly halted under the exclusive control of the damping subcircuit.

With the servomechanism holding either its open or closed null position, the motor damping winding is energized by the damping subcircuit to offer a resistive force to any sudden manual force, i.e., a force resulting from in or out wind gusts, children or the like tending to move the door away from its open or closed position. In the event the door is moved off its open or closed position, the network is unbalanced and the servomechanism immediately seeks its null position. Thus, even though forces temporarily displace the door when in its open or closed position, the door is promptly and automatically returned to its former position. Moreover, within a limited angle about the null position, the restoring torque is proportional to the displacement of the door.

The operator is adapted to be set to automatically open and close the door on a selected side of the doorway b-y adjustment of the control circuit. Although the door is automatically opened and closed on one side of the doorway, it may be panic operated on the other side of the doorway without rendering the door operator ineflfective. After panic or manual movement, the door is returned to its closed position under the control of the potentiometer network which is unbalanced by the panic movement of the door. Hence, after manual release of the door the servomechanism seeks its door closed null position and when the door reaches its closed position, the operator is able thereafter without readjustment or repair to automatically open and close the door. Furthermore, by proper adjustment of the treadle mat subcircuit the operator is conditioned to function as a double-acting door closer so that after the door has been manually opened on either side of the doorway thereby to unbalance the potentiometer network, the door is'returned to its closed position under the control of the unbalanced network.

Referring now' to the drawings, and in particular to FIG. 1', an entrance 20 is illustrated as including a doorway construction 22 provided in a wall 23. The doorway construction 22 is an integral unit and comprises a pair of jamb members 24 and 26 interconnected by a transom tube 28 and a transom window 30. An electric door operator 32 embodying the principles of the present invention is shown in dotted lines within the transom tube 28 and is drivingly connectely to a door 34 through an upper pivot pin or door spindle 36 extending into the transom tube 28. The door 34 swings horizontally within the doorway construction 22, and more particularly, is pivotally supported adjacent to one of its vertical edges by the upper pivot pin 36 and a lower angulated pivot pin 38 connected to the lower end of the jamb 26. A treadle mat 42 is supported on the floor 40 and extends perpendicularly from the wall 23 in the direction of trafiic through the doorway, the mat 42 having an entrance side 42a on the right side of the doorway 22 and an exit side 42b on the left side of the doorway.

The electric door operator 32 is selectively singleacting, i.e., it is adjusted to automatically open and close the door 34 on either side of the doorway 22 and, accordingly, the operator 32 operates only in response to the passage of one way traffic through the doorway. For example, as shown, the door 34 opens and closes on the left side of the doorway 22, as viewed in FIG. 1, and therefore the direction of traffic is from the right side to the left side of the doorway 22. Very briefly, the

operator 32 comprises a positional servomechanisrn which either seeks or holds a door in its open or closed position under the control of an electrical control circuit. Accordingly, the door 34 is at all times directly powered and controlled by the operator 3 2. a

As best shown in FIG. 2, the servomechanism inc-ludes an electrical servomotor 44 in driving engagement with the door 34 through a gear assembly 46 and the upper door pivot 36. A potentiometer circuit, indicated generally by the reference numeral 47, is unbalanced by a treadle mat subcircuit, indicated generally by the refer ence numeral 49 in response to actuation of the treadle mat 42, thereby to provide a driving voltage for energizing a control winding 48 of the motor 44 to either open or close the door 34. The network 47 is rebalanced by a follower or feedback device 50 in driving. engagement with the upper door pivot 36, which follower device 50 controls the magnitude of the driving voltage in accordance with the position of the door and reduces the driving voltage to zero when the door reaches its desired position. The electrical control circuit further includes (FIG. 7) a damping subcircuit, indicated generally by the reference numeral 52, operable to energize a damping winding 56 of the motor 44 whenever the door 34 has moved 60 of its open and closing movement. The energization of the damping winding 56 occurs during the last 30 of travel to efdamping subcircuit 52, a motor interrupting subcircuit 54 (FIG. 7) is operated to temporarily deenergize the control winding 48 of the servomotor 44 to assure that the motor promptly slows down to the latching speed.

SERVOMOTOR Considering now the electric door operator in greater detail, the motor 44, shown diagrammatically in FIGS. 2 and 8, is a conventional two-phase, squirrel-cage ininduction motor and as is well-known, has particular application where controlled power is essential. it is characterized by its ability to deliver nearly constant torque in either direction of rotation at speeds ranging from zero to over twelve hundred revolutions per minute and is capable of changing direction almost instantaneously.

The rotor of the squirrel-cage motor 44 has no windings and rotates in response to a rotating magnetic field produced by two separate field windings, i.e., the control winding 48 and a reference Winding 60, the winding 60 being continually energized from an A.C. source 63. The windings are supplied with alternating voltages differing in phase by substantially ninety electrical degrees and to this end a condenser 62 is serially connected in the circuit for energizing the reference winding 60. The direction of rotation of the motor depends on the angular direction of rotation of the magnetic field, while the field rotation depends upon the phase relationship of the voltages across the control winding 48 and the reference winding 60. Thus, if the voltage across the control Winding 48 leads the voltage across the reference winding 60, the motor 44 will rotate in a first direction while if the voltage across the control winding. 48 lags the voltage across the reference winding, the motor 44 will turn in an opposite direction. Whenever the electric operator 32 is turned on, an A.C. voltage having a constant magnitude is impressed across the reference winding 60. However, in normal operation, the control winding is energized with an A.C. voltage only when the mat subcircuit 49 effects an unbalance in the network 47. In fact, it is the network 47 which controls both the magnitude of the driving voltage in the control winding 48 and the relative phase relation between the voltages in the control and reference windings 48 and 64), thereby to control the magnitude of motor torque and direction of motor rotation to obtain the desired door movement.

The servomotor 44 further includes a damping winding 56 which is energized by a constant voltage DC. power circuit 58 under the control of the damping subcircuit 52, thereby to produce a stationary magnetic field within the space occupied by the rotor. The stationary magnetic field induces currents within the rotating rotor, with the result that an opposing magnetic field is developed to retard or resist the normal rotation of the rotor. Since the magnitude of the current induced within the rotor is proportional to the speed of the rotor, the resistance offered by the opposing magnetic field is directly proportional to the speed with which the rotor turns. Accordingly, when the rotor is turning at a normal rotary speed, a particular amount of resistance to rotation is offered, while as the rotor decreases in speed, progressively less resistance is offered to rotation of the rotor. Furthermore, when the rotor is stopped, no opposing resistance exists since no field currents are induced in the stationary rotor and no opposing magnetic field is produced.

6 GEAR ASSEMBLY The door driving force is transmitted from the motor 44 to the upper door pivot 36 through the gear assembly 46. Specifically, the driving connection, as shown in FIG. 2, extends from a Worm gear 64 mounted on the output shaft 44a of the motor 44 through a helical gear 66 secured to a vertical shaft 79 rotatably sup ported from the transom tube 28, through a drive pinion 68 secured to the shaft 70, to an intermediate gear 72 secured to a second vertical shaft 76 rotatab'ly supported from the transom tube 28, and an intermediate pinion 74 secured to the shaft 76, and then to a bull gear 78 fixedly secured to the upper door pivot pin 36. As shown, the gear assembly 46 is of simple design and, since it is required to handle a relatively large amount of torque or power, the gears in the assembly 46, with the exception of the helical gear, are made from hardened steel While the shafts and 76 and the lower door pivot 32 are also hardened.

POTENTIOMETER NETWORK The potentiometer network 47 illustrated diagrammatically in FIG. 2 and in detail in FIG. 4, comprises a self-balancing A.C. type bridge network which supplies a driving voltage to the motor control winding 48 for effecting the opening or closing of the door 34 in response to actuation of the treadle mat subcircuit 49 by a person walking through the doorway 22. In FIG. 2 certain of the transformer windings and circuit connections shown in FIG. 4 have been omitted for the sake of simplicity but similar reference numerals refer to similar parts. Referring particularly to FIG. 4, the bridge network has a first branch comprising a secondary winding 92 of a step-up reference transformer having its primary winding 91 connected across the A.C. voltage source 63 and has a second branch comprising a variable autotransformer 94, for example, a Variac, connected in parallel with the winding 92.

The A.C. bridge network further includes a center arm 96 having its first end 96a connected to a switch 97 which is operated by and forms a part of a control relay 160 and which is adapted to be moved under the control of the treadle mat subcircuit 49' (FIG. 2) to one of two diiferent voltage levels on the winding 92. The second end 96b of the center arm 96 is connected to a slider 99 movable along the winding 94 to different voltage levels. A primary winding 98 of a suitable step-up transformer is serially connected in the arm 96 while the secondary winding 95 of the step-up transformer is serially connected in circuit with the motor control winding 48. When the servornechanism is holding an open or closed null position, the ends 96a and 96b of the center arm 96 are connected to the same voltage levels; however,

' when the treadle subcircuit causes an unbalance in the network 47 and the servomechanism is seeking an open or closed null position the ends 96a and 96b of the center arm 96 are located at different voltage levels, thereby to provide a resultant driving voltage for the motor control winding 48.

More specifically, the approximate volts of the A.C. voltage source 63 is stepped up to volts by the reference transformer 90 so that the 140 volts appear across the first branch 92 of the A.C. bridge network 47 as well as the second branch 94. Accordingly, equal voltages exist at identical points or levels on the windings 92 and 94. When the servomechanism is in its door closed null position and the door is closed, the end 96a of the center arm 96 is connected through the switch 7 O 97 to a voltage level 100- on the winding 92 while the end 75 rent flows through the center arm and no voltage is developed in the motor control winding 48. However, when the treadle mat subscircuit is actuated, the switch 97 is moved from the voltage level 100 to a voltage level 104 on the winding 92. Since the slider initially remains at the voltage level 102, a voltage difference exists across the arm 96 to produce in the motor control winding 48 a driving voltage having a phase leading the voltage in the reference winding 60 by substantially 9O electrical degrees. The servomechanism thus seeks a door open null position and opens the door 34. During the opening movement of the door the follower device 50 (FIG. 2) moves the slider 99 along the winding 94 to control the magnitude of the driving voltage, as described below, until the door reaches its open position wherein the slider 99 is moved to a voltage level 106 on the winding 92 which is equal to the voltage level 104 on the winding 92. No voltage difference exists across the arm 96 and no current flows through the center arm 96 with the result that the motor 44 is deenergized. Thus, the bridge network 47 is rebalanced and the servomechanism holds its door open null position. In an electric door operator built according to the present invention, the servomechanism is designed to be slightly underdamped with the result that the Servomechanism slightly overshoots the door open null position. Specifically, the slider 99 slightly overshoots the voltage level 106 to produce in the control winding 48 a driving voltage having a phase lag ging the voltage in the reference winding 60 by substantially 90 electrical degrees, thereby causing the slider 99 to return to voltage level 106.

In response to deactuation of the treadle mat subcircuit, the network 47 is again unbalanced and the switch 97 is returned to the voltage level 100 on the winding 92 thereby to provide across the center arm 96 a voltage differential. This voltage diiferential develops across the motor control winding 48 a driving voltage having a phase lagging the voltage in the reference winding 60 by 90 electrical degrees, thereby to cause the motor 44 to rotate in a direction opposite to that described above to close the door. The servomechanism now seeks its door closed null position. During the closing movement of the door, the slider 99 is moved along the winding 94 under the control of the follower device 50 back to the voltage level 102 on the winding 94, which voltage level 102 is equal to the voltage level 100 so that no current flows through the center arm 96 and the motor control Winding 48 is deenergized. It will be appreciated that as the servomechanism seeks either its door open or door closed null position, the magnitude of the driving voltage applied to the motor control Winding 48 is dependent upon the relative position of the switch 97 and the slider 99. However, when the s-ervomechanism holds either its door open or closed null position, the magnitude of the driving voltage is Zero and the switch 97 and the slider 99 are at the same voltage levels.

FOLLOWER DEVICE The follower device 50 illustrated diagrammatically in FIG. 2 feeds back to the AC. bridge network 47 information regarding the position of the door 34 and thus effects the balance of the network 47. When the operator is functioning to automatically open and close the door 34, the follower device 50 rebalances the network 47 unbalanced by the mat subcircuit 49 and, accordingly, reduces the magnitude of the driving voltage in the motor control winding 48, while, when the operator functions as a door closer or is panic operated, the follower device 50 actually unbalances the network 47 to produce a driving voltage forthe motor control winding 48 and thereafter rebalances the network to reduce the magnitude of the driving voltage. Assuming the operator 32 is set for automatic operation, the follower device 50 during movement of the door 34 moves the slider 99 along the winding 94 and provides a driving voltage having an initially high magnitude for overcoming the inertia of the structure and 8 quickly moving the door, a lower constant magnitude for moving the door at an optimum speed, and finally a magnitude decreasing to zero for limiting overshooting or hunting of the door. To this end, a cam and rack arrangement are connected between the AC. bridge network 47 and the gear assembly 46 which has its shaft 76 win driving engagement with the door 34 through the gear 74, gear 78 and the door pivot 36. A cam is fixedly secured to the upper end 76a. of the shaft 76 and comprises a disk provided on its upper surface with a continuous carnming groove 112, as best shown in FIG. 3. A follower roller or pin 114 of an elongated bar 116 continuously engages the groove 112 and effects reciprocal movement of the bar 116 incident to rotation of the cam 110, the bar 116 being supported from a roller bearing structure mounted on the transom tube 28. The right end of the follower bar 116 as viewed in FIG. 2 is provided with a plurality of rack teeth 118 which engage a pinion 120 supported at the upper end of a shaft 122 on which the slider 99 is mounted. The slider 99 is thus rotated by an amount proportional to the displacement or move ment of the follower bar 116 which, in turn, is controlled by rotation of the cam 110 in response to door movement.

Considering now in greater detail the cam 110 and in particular the configuration of the continuous camming groove 112, attention is directed to FIG. 3. The continuous groove 112, defined in the upper surface of the cam 110, has a substantially constant width slightly greater than the diameter of the pin 114 so that the pin 114 freely rides in the groove but does not rattle or appreciably move transversely of the groove 112. It comprises an automatic groove section 132, 133, 134 intermediate an outer panic groove section 130, 131 and an inner panic groove section 135, 136. The automatic groove section comprises a straight groove portion 132, an arcuate groove portion 133, and a straight groove portion 134; the outer panic groove section comprises a straight groove portion 131 and an 'arcuate groove portion and the inner panic groove section comprises a straight groove portion and an arcuate groove portion 136.

If the closer 32 is set to open the door on the left side of the doorway 22, the cam 110 is in such a position that the follower pin 114 is located in the outer end of the straight groove portion 132, in the position shown in dotted lines and identified as 137. With the follower pin 114 in this position, the rack 116 causes the slider 99 to be located at the voltage level 102. FIG. 12 shows a diagram of the magnitude of the voltage of the end 96b and the slider 99 as it is moved under the control of the cam 110 during a conventional automatic opening and closing of the door 34. During the first 2 /2 degrees of door opening movement, the cam 110 rotates in a counterclockwise direction and the follower pin moves along the portion 132 thereby to displace the bar 116 and move the slider 99 from the voltage level 102 to voltage level 105. During the movement of the door from its 2 /2 degree open position to its 87 /2 degree open position, the cam 110 rotates and the follower pin 114 travels in the arcuate groove portion 133 (as shown) with the result that the bar 116 is not moved and the slider 99 remains at the voltage level 105. During the last 2 /2 degrees opening movement, i.e., 87 /2 degrees to .90 degrees, the cam 110 rotates so that the follower pin 114 travels along the groove portion 134 thereby to displace the follower bar 116 and move the slider 99 from the voltage level 105 to the voltage level 106. The pin 114 is now at the inner end of the groove portion 134 as shown in dotted lines and identified by reference numeral 138. As long as the door remains open, the slider 99 remains at the voltage level 106. During closing of the door, the cam rotates in a clockwise direction and the follower pin moves from the point 138 through the groove portions 134, 133, 132 back to the point 137 thereby to move the slider from the voltage level 106 back to the voltage level 102, as shown by the arrows pointing to the left in FIG. 12.

The magnitude of the driving voltage applied to the motor control winding 48, the magnitude of the voltage at the first end 96a of the arm 96 (i.e., the switch voltage 97) and the magnitude of the voltage at the second end 96b of the arm 96 (i.e., the slider voltage 99) is illustrated in FIG. for automatic opening and closing of the door on the left side of the doorway 26. The opening and closing movements of the door are also illustrated in FIG. 9 and are identified by reference letters A and B, respectively. In FIG. 10, the slider voltage is indicated by reference numeral 99 and is shown in full lines, the voltage at the switch 97 is identified by the numeral 97 and is shown in crossed lines, and the driving voltage which is proportional to the difference between the switch and slider voltages is illustrated by arrowed lines 48a drawn vertically between the switch and slider voltages. When the door is in its closed positionand the servornechanism holds its door closed null position, the switch voltage and the slider voltage are at equal voltage levels 100 and 102, respectively. However, when the switch 97 is moved from the voltage level 100 to the voltage level 104 under the control of the treadle mat subcircuit, the network 47 is unbalanced to apply an initial-1y high driving voltage to the motor control winding 48 with the result that a high torque is developed to overcome the inertia of the door structure and quickly open the door. As the door opens, the follower pin 114 moves inwardly along the groove portion 132 to move the follower bar 116, thereby linearly to increase the slider voltage 99 and linearly decrease the voltage difference between the switch and the slider voltages. After 2 /2 degrees of door opening movement the follower pin 114 reaches the groove portion 133 and the slider 99 reaches the voltage level 105 with the result that the driving voltage reaches an intermediate value. The slider voltage remains at the voltage level 105 and the driving voltage remains at its intermediate value until the cam has rotated substantially one revolution and the door is in an 87 /2 degree open position. As the pin 114 moves in the groove portion 134 to again displace the bar 116, the slider voltage linearly increases while the driving voltage linearly decreases. When the follower pin 114 reaches the point 138, the slider 99 is at the voltage level 106 and the switch 97 is at voltage level 104. Thus, since voltage levels 104 and 106 are equal, the voltage at the ends 96a are equal with the result that no voltage difference exists across the center arm 96. Accordingly, the network 47 is rebalanced and no driving voltage is developed for the motor control winding 48.

The servomechanism holds its door open null position under the control of the treadle mat subcircuit and holds the door open as long as the mat subcircuit is not disturbed. If for any reason a force is applied to the door to move it either toward its closed position or toward a further open position, the cam 110 rotates and the follower pin 114 moves along the groove portions 134-135, thereby moving the slider 99 from the voltage level 106 toward either of the voltage levels 105 or 107 (FIG. 12). Accordingly, the follower device 50, instead of the treadle mat subcircuit, unbalances the bridge network 47 and the motor control winding is energized with a driving voltage having the necessary phase to return the door to its open position and the slider 99 to the door open null position 106. It should be observed that as the door moves farther from its open position, within a 2 /2 degree range in either direction, the magnitude of the driving voltage progressively increases to pro duce a progressively greater torque for returning the door to its open position. As described above, when the door is returned to its open position the network 47 is rebalanced and the driving voltage is reduced to zero.

The door is closed under the control of the treadle mat subcircuit by the switch 97 being moved from the voltage level 104 to the voltage level 100, thereby to unbalance the network 47 and cause the servomechanism to seek its door closed null position. The unbalanced network 47 develops a driving voltage which is so phase related to the voltage in the reference winding 60 to cause the motor to rotate in a direction opposite to that above, thereby to return the door to its closed position. As shown, the magnitude of the driving voltage during closing of the door is identical to the magnitude of the driving voltage during opening of the door and initially has a high value, a substantially constant intermediate value, and a value which decreases to zero. The follower pin moves from the point 138 to the point 137 along the groove portions 134, 133, 132 in exactly the reverse manner as described above. The slider 99, of course, moves from the voltage level 104 to the voltage level 105 between the degree and 87 /2 degree open positions, remains at the voltage level between the 87 /2 degree to 2 /2 degree open positions, and moves from the voltage level 105 to the voltage level 102 between the 2 /2 degree open position to the closed position. When the follower pin 114 reaches the point 137, the slider voltage 99 is at voltage level 102 and the switch voltage 97 is at voltage level 100 with the result that the network 47 is rebalanced and the magnitude of the driving voltage is reduced to zero. The servomechanism now holds the door closed null position and retains the door in its closed position even though no driving voltage is supplied to the motor control winding 48. Thus, when drafts, Wind currents, or the like tend to move the door away from its door closed position, it is the follower device 50 which unbalances the network 47. Specifically, the cam r110 rotates and the follower pin 114 moves along the groove portion 131-132 thereby to move the slider 99 toward either the voltage level 101 or 105 to unbalance the network 47 and produce for the motor control winding a driving voltage having a proper phase relative to the reference winding 60 to return the door to its closed position.

If the door operator is set to open and close on the right side of the doorway 22 (i.e., to etfect opening movement C and closing movement D as shown in FIG. 9), then the cam is moved as described hereinafter so that the follower pin 114 is located at the point 138 when the door 34 is in its closed position. In the same manner as described above, the follower pin travels from the point 138 through the groove portions 134, .133 and 132 to the point 137 and then back to the point 138 while the slider 99 moves from voltage level 106 to voltage levels 105 and 102 and back to voltage level 106 during automatic opening and closing of the door.

Furthermore, when the operator 32 is set to automatically open and close the door 34 on the left side of the doorway 2d and the door is panic opened on the right side of the doorway 22, the follower device 50 unbalances the network 47 and develops a driving voltage for automatically returning the door to its closed position. The earn 110 rotates clockwise to cause the follower pm 114 to move from the point 137 into the groove portions 131 and 130, the follower pin 114 reaching the groove portion and the slider 99 moving from the voltage level 102 to the voltage level 101 after 2 /2 degrees of opening movement. Beyond the 2 /2 degree open position, the pin 114 remains in the groove portion .130 while the slider 99 remains at the voltage level 101. incident to manual release of the door, the unbalanced network -47 causes the door to be automatically closed, whereby the pin 1'14 returns along the groove portions 130 and 131 to the point 137 while the slider 99 returns to the voltage level 100. When the operator is set to open the door 34 on the right side of the doorway 22 and the door is panic opened to the left side of the doorway 22, the follower device 50 unbalances the network 47 and develops a driving voltage for automatically returning the door to its closed position. The cam 110 rotates counterclockwise to cause the follower pin to travel from the point 138 into the groove portions 135 and l 1 136 and the slider 99 to move from the voltage level 106 to the voltage level 107 within 2 /2 degrees of door opening movement.

In'the event the operator is set to open on the left side of the doorway and is conditioned to act as a double-acting door closer, incident to manual opening of the door on the left side of the doorway, the follower device 50 unbalances the network 47 and produces a driving voltage. The cam 1'10 rotates counterclockwise and thg follower pin 114 moves from the point 137 into the groove portions 1 3-2 and 133 with the result that the slider moves from the voltage level 102 to voltage level 105 within 2 /2 degrees of opening movement. Between the 2%. degree and 87 /2 degree open positions, the pin 114 remains in the groove portion 133 while the slider 99 remains at the voltage level 105 and between the 87 /2 degree and 90 degree open positions, the pin 114 moves along the groove portion 134 thereby to cause the slider 99 to move from the voltage level 105 to the voltage level 106. When the door is manually released, the unbalanced network 47 automatically causes the door to return to its closed position, whereby the pin 114 returns to its point 137 and the slider 99 returns to its voltage level 102. As the door is opened to the right side of the doorway, the cam rotates clockwise and the follower pin 1'14 moves from the point 137 into the groove portions 131 and 130 thereby to move the slider 99 from the voltage level 102 to the voltage level 101. During automatic closing of the door, the pin returns to its point 137 and the slider 99 returns to its voltage level 102. In the event the operator is set to open on the right side of the doorway 22 and is conditioned to act as a double-acting door closer, then incident to manual opening of the door on the left side of the doorway, the cam 110 rotates counterclockwise and the follower pin 1:14 moves from the point 138 into the grooves 135, 136 while the slider moves from voltage level .106 to voltage level 107. Incident to manual opening of the door on the right side of the doorway, the cam 110 rotates clockwise and the follower pin i114- moves from the point 138 into the grooves 134, 13-3 and 132 while the slider moves from voltage level 106 to voltage levels 5 and 102.

CONTROL CIRCUIT Considering now the control circuit and referring particularly to FIG. 8, the circuit includes a pair of power conductors 23-7 and 239 which are connected to the AC. voltage source 63, which, for example, may com-prise 60 cycle electrical power supplied to buildings, dwellings and the like. The power for operating the electric door operator 32 is supplied by these conductors and is controlled by an on-oif switch 139 which is serially connected in the power line 239 and is mounted, as shown in FIG. 1, to the jamb 24 to be readily accessible to manual actuation. A fuse 141 is also serially connected in the power line 239 while a motor fan 142 is connected across the lines 237 and 239 to provide continued air circulation in the transom tube by drawing air through a vent 40a into the tube and forcing air out of the tube through a vent 40b.

The power conductor 237 is grounded and is connected to one end of the primary win-ding 91 of the reference autotransformer 90 while the conductor 239 is connected to an intermediate point on the autotransformer winding 91, thereby to provide a voltage of 140 volts across the entire primary 91. This winding 91 causes an A.C. voltage to be developed across both the secondary winding 92 and the Variac winding 94 comprising the two branches of the Waxwell bridge network 47 and further supplies the power for the D.C. power supply circuit 58. A portion of the secondary winding turns, identified as 143, is used as a low voltage A.'C. source, i.e., 12 volts, and supplies power to certain ones of the relays in the treadle mat subcircuit 49.

In order to energize the damping winding 56 during a damping operation with a D.C. current, the electric door Specifically, the circuit 58 is of the conventional rectifier type and is connected in parallel with the primary winding 91 of the transformer 90. The stepped up 140 volts appearing across the circuit 58 is rectifiedby a pair of serially connected silicon rectifiers 123 and 124, which rectifiers are further serially connected with a resistor 126 and a capacitor 128, one plate of which is connected to the grounded conductor 237. The capacitor is employed to filter the ripple voltage obtained from the rectifiers and to provide a substantially constant D.C. voltage of approximately 175 volts. The resistor 126 functions as a current limiting device to prevent the first instantaneous charge current from overheating the rectifiers 123 and 124. A resistor 130 is connected in parallel across the condenser 128 to provide a discharge path for the charge on the condenser when the power to the electric door operator 32 is turned off by the switch 139. As shown, the 175 volts is available at the junction of the capacitor 128 and the rectifier 124 which junction is hereafter identified as the positive terminal 144 of the D.C. power supply circuit 58. As described in greater detail hereinafter, the 175 volts of the D.C. power supply circuit 58 is used to energize the damping winding 56 of the motor 44 and to energize a relay in the treadle mat subcircuit.

l. T readle Mat Subcircuit Considering now the treadle mat subcircuit and referring specifically to FIGS. 2 and 8, the circuit comprises the treadle mat '42 which embodies an entrance footoperated switch having a pair of normally open contacts 81 and an exit foot-operated switch 82 also having a pair of normally opened contacts 83. When a person steps on the mat entrance side 42a and closes the switch contacts 81, an operate relay 140 is energized to close a pair of its contacts which complete a circuit for energizing a control relay 160. The control relay 160 01)- erates to unbalance the Maxwell bridge network 47 by moving the switch 97 from the voltage level 100 to the voltage level 104 with the result that the servomechanism is caused to seek a door open null position. As the person walks from the mat entrance side 42a to the mat exit side 42b, the entrance contacts 81 are opened and the exit contacts 83 are almost simultaneously closed, whereby a safety relay 150 is operated to close a pair of contacts which completes another circuit (shown only in FIG. 8) for energizing the control relay 160, which latter circuit is independent of the operate relay so that the control relay 160 remains energized even though the entrance contacts open to deenergize the operate relay 140. As shown in the greatly simplified circuit of FIG. 2, the operate relay 140 and the safety relay are interrelated so that the control relay is energized through the operate relay 140 only when the safety relay 150 is unenergized. Accordingly, if someone stands on the mat exit side 42b, thereby to close the exit switch contacts 83 and operate the safety relay 150 to open the energizing circuit for the control relay 160, and thereafter a person steps on the mat entrance side 42a to energize the operate relay 140, the control relay 160 does not operate so that the network 47 remains balanced and the door remains in its closed position. Accordingly, an inattentive per- 'son standing within the range of opening movement of the door is not injured by the opening door since the door is rendered ineffective by the presence of the person on the mat exit side 4212.

Referring now more specifically to FIG. 8, in which the relays, switches and contacts are shown in the position they assume when the door is in its closed position, as a person walks through the entrance 20, he first steps on the entrance side 42a of the mat 42 and actuates the mat entrance switch 80 to close the switch contacts 81. The closure of the switch contacts 81 completes an energizing circuit for the operate relay 140 from ground, a conductor 145, switch contacts '81, a conductor 14 6, a

- 13 winding 140a of the operate relay 1 40, a conductor 147, the 12 volt A.C. power source 143, a conductor 148 and to ground. The operation of the relay 140 causes a single pair of contacts 149 to close, thereby to complete an energizing circuit for the control relay 160 as follows: the

positive terminal 144, a conductor 151, a current limiting resistor 153, a conductor 155, the contacts 149, a conductor 157, contacts 154, conductor 159, the relay winding 160a of the control relay 160, a conductor 161, the power conductor 237, to ground. The energization of the control relay 160 causes the contact wiper 97a of the switch 97 to disengage a contact 10011 and to engage a contact 104a, and further causes a pair of contacts 162 to open, a pair of contacts 164 to close, and a pair of contacts 166 to close. The closure of the contacts 97a-10 4a causes the end 96a of the arm 96 to be disconnected from the voltage level 100 and connected to the voltage level 104 through the following circuit: a conductor 163, a socket 165, a plug 167, and -a conductor 168. As indicated above, the movement of the switch 97 unbalances the network 47 which produces a driving voltage for the motor control winding and efiects the opening of the door. The closure of the contacts 164 disconnects a door position-sensitive switch 174 from and connects a door position-sensitive switch 170 to the damping winding 56 for a purpose described hereinafter. The closure of the contacts 166' completes a holding circuit for the control relay 160 so that the control relay remains energized independently of the safety relay 150. The conductor 159, the contacts 166 and a conductor 169 comprise part of the holding circuit and are in parallel with the contacts 154 so that even though the safety relay 150 is energized and its contacts 154 open, the control relay remains energized.

As a person passes from the mat entrance side 42a to the mat exit side 42b, the mat exit contacts 83 usually close a short time interval after the opening of the mat entrance contacts 81, with the result that for about a quarter of a second the operate relay 140 is deenergized thereby to open both the energizing and holding circuits [for the control relay 160. This quarter of a second time interval generally occurs while the door is opening. In order to maintain the control relay 160 energized during this time interval, a condenser 173 is connected across the control relay winding 1 60a to be energized by current from the DC. positive terminal 144 during closure of the mat entrance contacts 81. Hence, during the short time interval that the energizing circuit for the control relay 160 is open, the charge stored in the con- .denser 173 discharges through the control relay winding 160a thereby to maintain the control relay 160 energized during the quarter of a second time interval.

The person stepping on the mat exit side 4212 causes the exit switch contacts 83 to close, thereby to complete an energizing circuit for the safety relay 150. Specifically, the circuit is from ground, a conductor 145, contacts 83, conductor 177, the relay winding 15021 of the safety relay 150, a conductor 178, the 12 volt A.C. source 143, the conductor 239, and ground. The energization of the safety relay 150 efiects the closure of contacts 152 and 158 and the opening of contacts 154 and 156. The closure of the contacts 152 completes a second energizing circuit for the control relay 160 from the positive terminal 144, the resistor 153, the conductor 155, a conductor 179, the contacts 152, the conductor 157, the conductor 169, the contacts 166, the winding 160a, the conductor 161, the conductor 237, and ground. Hence, the control relay 160 remains energized by the above described second energization circuit even though the operate relay 140 is deenergized and the first energization circuit for the control relay 160 is open circuited by the opening of the contacts 149 incident to the person stepping off the mat entrance side 42a.

The opening of the contacts 156 open circuits the connection between the contact 100a and the voltage level on the winding 92 but performs no useful function at this time, inasmuch as the left end 96a of the arm 96 is connected to the voltage level 104 through the switch 97 and contact 1114a. The above connection, as shown, comprises the contact 100a, a conductor 125, the contacts 156, a conductor 127, the socket 165, the plug 167, a conductor 129 and the voltage level 100. The closure of the contacts 158 causes the operation of the damping subcircuit with the attendant energization of the damping winding 56 in the event the door is closing, as described in greater detail below, but per-forms no useful function at this time because the contacts 162 are opened under the control of the control relay 160. The control relay 160 remains energized and the servomechanism holds the door open null position with the switch 97 at voltage level 104 and the slider at voltage level 106 as long as the person remains on the mat exit side 4212 and closes the mat exit contacts 83.

When the person steps off of the \mat exit side 42b thereby to open the contacts 83, the safety relay is deenergized and its contacts 152 are opened thereby to open the second energizing circuit for the control relay 160. The deenergization of the control relay does not occur immediately but is delayed approximately aquarter of a second while the charge on the condenser 173 discharges through the relay winding 160a. The denergization of the control relay 160 causes the wiper contact 97a to disengage the contact 184a and to engage the contact 100a, thereby to disconnect the end 960 of the arm 96 from the voltage level 104 and connect it to the voltage level 100. As described above, the network 47 is unbalanced and produces for the motor control winding 48 a driving voltage which causes the door to be moved to its closed position. Incident to deenergization of the safety relay 140 and the control relay 160, the relays, switches, and contacts assume the positions shown in FIG. 8.

2. Damping Subcircuit The damping subcircuit 52 is illustrated in FIGS. 7 and 8 and briefly functions to energize the damping winding 56 of the motor 44 during the last 30 degrees of door opening or closing movement, thereby to provide a door latching speed which is substantially slower than the normal opening and closing speed of the door. As illustrated in FIG. 2, a pair of door position-sensitive switches 171) and 174 are both actuated by a cam 180 during the first 30 and last 30 degrees opening and closing movement of the door and are selectively connected by the contacts 162, 164 under the control of the control relay 160 between the damping winding 56 and the DC. terminal 144. The earn 180 moves in response to movement of the door 34 and is fixedly secured to the upper end of the door pivot 36 for cooperation with the door position-sensitive switches and 174 supported on structure mounted on the transom tube 28. The cam 180* is disc shaped and has a 60 degree peripheral cam portion 180a for selectively engaging the contact actuating levers 170a and 174a of the switches 170 and 174. When the door is in its closed position, the cam engaging portion of the lever 174a is in engagement with the middle of the cam portion 180a so that irrespective of the direction of door movement the contacts 175 of the switch 174 are closed and the contacts 176 of the switch 174 are opened. In contrast, the cam engaging portion of the lever 170a is spaced from the cam portion 180a to be engaged by the cam 184) to close contacts 171 and open contacts 172 only after the door has been moved to a 60 degree open position on the right side of the doorway 22.

When the control relay 160 is energized in response to a person stepping on the mat entrance side 42a, the contacts 162 are opened thereby to open a first energization circuit described below for the damping winding and the contacts 164 are closed thereby conditioning a second circuit for energizing the damping winding 56. This circuit, referring to FIG. 8, is as follows: the terminal 144, a conductor 181, a current limiting resistor 182, a conductor 183-, open contacts 171, the socket 165, the plug 167, the conductor 184, the closed contacts 164, a conductor 185, an inductor 186, the damping winding 56, the power conductor 237 and ground. Although the contacts 175 are closed by the cam 180 when the door is in its closed position, the motor damping winding 56 is not energized through the switch 174 since the contacts 162 are opened. The damping winding 56 is also not energized through the switch 170 in the door closed position and throughout 60 degrees of door opening movement since the contacts 171 are opened. When the door reaches its 60 degree open position the switch contacts 172 are opened and the contacts 171 are closed with the result that the above described second energization circuit for the damping winding 56 is completed and current flows through the winding 56 to effect a damping of the motor as described above. Current flows through the damping winding 56 during the movement of the door between its 60 degree and 90 degree open positions and also as long as the door remains in its door open position. Incident to deenergization of the control relay 160 by the treadle mat subcircuit 49, the contacts 164 are opened thereby to open the above described second energization circuit for the damping winding 56 and the contacts 162 areclosed to condition the first energization circuit for the damping winding 56 to operate as follows (FIG. 8): the DC. terminal 144, the conductor 181, the resistor 182, the conductor 183', the open contacts 175, the socket 165, plug 167, a conductor 187, contacts 162, conductor 185, the inductor 186, damping winding 156, power conductor 237, and ground. Hence, the control relay 160 serially connects the switch 174 to the damping winding 56 and disconnects the switch 170 from the damping winding so that even though the contacts 171 remain closed the damping winding 56 becomes deenergized. When the door reaches its30 degree open position, the cam portion 180a actuates the switch 174 with the result that the contacts 176 open and the contacts 175 close, thereby to complete the first energizing circuit through contacts 162 for the damping Winding 56. The damping winding 56 of the motor 44 is energized during the movement of the door 34 from its 30 degree open to its closed position and remains energized for as long as the door is in its closed position.

It should be appreciated that the inductor 186 is serially connected with the damping winding to reduce the torque loss resulting from the interaction of the magnetic fields developed by the control and damping windings. In a commercial embodiment of the present invention, the control and damping windings are wound on the same slots of the stator with the result that the windings act like the primary and secondary of a transformer. When ever the damping winding 56 is energized the capacitor 128 of the DC. voltagesource circuit 58 is connected in parallel across the damping winding 56 with the result that the capacity is reflected into the control winding 48. The capacity in the control winding 48 causes a phase shift of the current flowing in the control winding 48 and a resulting loss of torque. The inductor 186, thus, reflects a large inductance into the control winding 48 and cancels out the eifect of the capacitor 128 without loading the control winding circuit. It should be appreciated, however, that the damping windings may alternatively be wound on slots other than the slots on which the control windings are wound and, accordingly, the indicator 186 may be eliminated from the circuit.

3. Motor Interrupting Subcircuit The motor interrupting subcircuit 54 is shown in FIGS. 7 and 8 and has two specific functions. First, during opening and closing of the door it open circuits the motor control winding 48 for .a predetermined time interval and simultaneously energizes the damping winding 56, thereby to permit the door 34 to bearrested under the X-' clusive control of the damping winding 56 and to cause the door 34 to move slowly into either its open or closed 16 position. Second, it prevents fingers from being crushed or injured between the free moving door 34 and the door jamb 24 as a result of a person stepping on the mat entrance side 42a during the predetermined time interval. 1

Referring particularly to FIG. 7 in which the positions of the subcircuit relays, switches and contacts are shown when the door 34 is in its closed position, the subcircuit 54 comprises a pulse relay 198 which, when energized under the control of the door switches and 174,

causes a pair of contacts 192 serially connected to the center arm 96 of the bridge network 47 to be opened and a pair of contacts 194 serially connected directly between the D0. terminal 144 and the damping winding to be closed. The subcircuit 54 is in a static condition, i.e., the relay 190 is set, when the contacts 172 of the door switch 170 and the contacts 176 of the door switch 174 are both closed. Then, when either of the contacts 172 or 176 are opened, the circuit 54 is operative to energize the relay 190 for a predetermined period of time during which the motor control winding 48 is open circulated and the damping Winding is directly energized from the DC. terminal 144. More specifically, the coil 190a of the relay 190 is connected in parallel with a serially connected rectifier 196 and a resistor 198, the parallel network being serially connected with a condenser 280. Both the parallel network and the condenser 200 are connected in parallel .across the contacts 172 and 176 of the door switches 170, 174. The junction of the relay coil 190a and the resistor 198, identified as 202, is connected to the terminal 144 by a conductor 204 while the junction of the condenser plate 20% and one of the contacts 176, identified as 206, is serially connected through a current limiting resistor 208 to ground.

When the door is between the 30 degree and 60 degree door open positions, the subcircuit 54 is in tis static condition. Specifically, the 175 volts of the DC. terminal 144 is applied to each of the condenser plates 200a and 20% with the result that no current flows through relay winding a, condenser 200 and resistor 208. When the door reaches either its 30 degree or 60 degree open position, i.e., when it is 30 degrees adjacent to either its open or closed position, either one or the other of the contacts 172 or 176 is opened thereby to elfect the removal of the 175 volts from the condenser plate 20%. Hence, because of the voltage potential across the capacitor 200, current flows through the relay winding 190 to charge the condenser 200, the current flow being from the terminal 144 through the relay winding 198a, the condenser 2.00, the resistor 20 8 and ground. No current flows through the parallel branch comprising the resistor 198 and the silicon rectifier 196 because of the high resistance offered by the rectifier 196. The time pulse relay 190 is thus energized by the condenser charging current and it remains energized for a predetermined time interval until the condenser approaches full charge and the condenser charging current is reduced to a value less than that necessary to hold up the relay 190.

The energization of the relay 190 efiects the opening of the contacts 192 and the closureof the contacts 194. The opening of the contacts 192 open circuits a conductor 210 connected between the end 96b and the primary winding 98 and the closure of the contacts 194 completes a third energization circuit for the damping winding as follows (FIG. 8): the DC. terminal 144, conductor 181, resistor 182, a conductor 212, contacts 194, a conductor 214, the inductor 186, the damping winding 56, power conductor 237, and ground. This latter circuit eiTectively bypasses the switches 170 and 174 and energizes the damping Winding 56 irrespective of the positron of the switch contacts 171, 172, 175 and 176. After the predetermined time interval the relay 190 is deenergized and the contacts 192 are closed and the contacts 194 are opened.

The circuit 54 is reset when the door moves between its 30 and 60 degree open positions and both the pair of contacts 172 and 176 are closed. The closure of the contacts 172, 176 provides a discharging path for'the condenser comprising the rectifier 196, the resistor 198, the contacts 172, 176 and the condenser 200. Only a small amount of current actually flows through the winding 190a since the resistance of the resistor 198 and the forward resistance of the rectifier 196 is one hundred times less than the resistance of the relay coil. Accordingly, only 1% of the total current flows through the winding 190a and this amount of current is inadequate to energize the relay 190. The condenser 200 is completely discharged and 175 volts is applied across the condenser plates 2110a. and 2110b within one second which is less than the time required for the door to move between its 30 degree and 60 degree positions.

AUTOMATIC OPERATION-DOOR OPENING Assuming that the operator is set to automatically open and close the door 34 on the left side of the doorway 22 and that the door is in its closed position, then the position of the control circuit switches, contacts and relays are as illustrated in FIG. 8. In the door closed position, the motor control winding '48 is deenergized and the motor damping winding 55 is energized under the control of the damping subcircuit 52.. When a person walks through the entrance 2i} and steps upon the mat entrance side 42a, the switch contacts 81 are closed thereby causing the energization of the operate relay 140, whereby the closure of its contacts 142 completes the first energizing circuit for the control relay 160. The control relay 166, however, is energized only in the event that the safety relay 156 is not energized and its contacts 154 are not opened. The energization of the control relay 1611 causes the opening of the contacts 97a-100a, the opening of the contacts 162 thereby to deenergize the damping winding 56, the closure of the contacts 97a104a, the closure of contacts 164 and the closure of contacts 166. The closure of the contacts 166 renders the safety relay contacts 154 ineffective while the closure of the contacts 164 connects the door position-sensitive switch 170 to the damping winding 56. The closure of the contacts 97a-104n causes the switch 97 to move from its voltage level 100 to the voltage level 104 on the winding 92 with the result that the network 47 is unbalanced and a voltage differential is developed across the center arm 96 of the potentiometer network 47 to provide a driving voltage through the stepup transformer to the motor control winding 48. Hence the servomechanism now seeks its door open null position. The relative phase relationship of the voltage in the control winding '48 and the reference winding 60 is such that the door opens on the left side of the doorway 22 while the magnitude of the driving voltage (proportional to the difference between the slider 99 and switch 97 voltages) applied to the control winding 48 is of such high initial magnitude that the door promptly opens (see FIG. The initially high driving voltage is linearly reduced to a substantially constant intermediate driving voltage within the first 2 /2 degrees of door movement under the control of the follower device 56, the slider 99 being moved from the voltage level 162 to the voltage level 195 under the influence of the cam 110. The intermediate driving voltage is applied to the control winding 48 between the 2%. degree to 87 /2 degree door open positions and effects an optimum opening speed of the door 34 between the 2 /2 degree to 60 degree door open position. Accordingly, the door is quickly opened and is moved at a speed to prevent a person from walking into the door when passing through the entrance 20 at a denser 2G!) is discharged the 175 DC voltage is applied to both plates of the condenser 200.

As the door reaches its 66 degree open position, the camming portion 180a of the cam 180 engages the lever arm 170a of the door switch 170 thereby causing the contacts 172 to open and the contacts 171 to close. By the opening and closing of these contacts, both the damping and motor interrupting circuits 52 and 54 are operated, the damping circuit 52 being operated during the remaining 30 degrees of door travel and the motor interrupting circuit being operated during only a predetermined time interval. The closure of the contacts 171 completes the second energizing circuit for the damping winding 56 from the terminal 144, the conductor 181, resistor 1S2, conductor '183, the closed contacts 171, the socket 165, plug 167, conductor 184, contacts 164, conductor 185, inductor 186, the motor damping winding 56, the conductor 237, and ground. The energized damping winding 56 produces within the space occupied by the rotor a stationary magnetic field which produces, as described above, a resistance to rotation. On the other hand, the opening of the contacts 172 removes the DC. voltage from the condenser plate 200]) with the result that the time pulse relay 190 is energized by the charging condenser current. The operation of the time pulse relay 19tl'causes, first, the contacts 192 to open thereby to open circuit the center arm 96 of the network 47 to deenergize the motor control winding 48 and, second, the contacts 194 to close thereby to complete the third circuit for energizing the damping winding 56 independently of the door switches 170 and 174. The relay 190 is operated for a time interval equal to the LC time constant of the charging circuit, which time constant is of such duration, for example, three-tenths of a second, to permit the energized damping winding to work at full eificiency to slow down the door motion. As shown in FIG. 10, when the door is in its 60 degree open position, the motor control winding 48 is deenergized for the threetenths of a second time interval and is then reenergized incident to deenergization of the time pulse relay 190. The motor damping winding 56, however, remains energized during the movement of the door between its 60 degree and degree open position and thereafter while the door is in its door open position, as illustrated in FIG. 11.

The door moves at latching speed from a few degrees after the 60 degree open position to approximately 87 /2 degrees open position since both the motor control winding 48 and the damping winding 56 are energized. Between the 87 /2 degree and 90 degree open positions, the magnitude of the driving voltage progressively decreases (see FIG. 10) under the control of the follower device 50 and in particular the control cam 110. During this 2 /2 degree movement, the motor 44 rotates and the door 34 moves at a progressively slower speed as it approaches its 90 degree open position so that the resistive force offered by the energized damping winding, being dependent upon the speed of rotation of the motor, likewise progressively decreases. Actually, the motor 44 is slightly under-damped so that the door moves fairly promptly into its 90 degree open position with only a minimum of overshoot past the 90 degree open position.

Typically, a person moves from the mat entrance side 42a to the mat exit side 42b while the door is opening and only infrequently does he move into the mat exit side 4212 after the door has completed its opening movement. In either case, the contacts 81 are opened thereby to deenergize the operate relay and almost simultaneously the contacts 83 are closed thereby to complete an energization circuit for the safety relay 150. The relay causes the closure of the contacts 152 to complete the second energization circuit for the control relay for maintaining the control relay 160 operated entirely independently of the operate relay 140. If a time interval exists between the opening of the contacts 81 and the 19 closure of the contacts 83, the time delay condenser 173 discharges current through the control relay winding 160a, thereby to maintain the control relay 160 energized during the brief interval.

The door 34 remains in its open position and the servomechanism holds its door open null position as long as the person remains on the mat exit side 4212. This is true even though a person walks off the mat entrance side 42a while the person stands on the mat exit side 42b. It should be observed, as clearly shown in FIGS. and 11, that in the door open position the control winding 48 is not energized while the damping winding 56 is energized and the potentiometer network is balanced with the switch 97 and the slider 99 at the same voltage levels, i.e., voltage levels 104 and 106, respectively. However, if the door 34 is manually moved toward its closed position or to a further opened position, the network 47 is unbalanced by the follower device 50 which causes the slider 99 to move away from the voltage level 106, thereby to create in the motor control winding a driving voltage having a polarity and magnitude to cause the door to be returned to its door open position. It should be noted that the greater the displacement of the door from its open position, the greater is the magnitude of the driving voltage applied to the motor control winding. This result is achieved because of the configuration of the cam 110 which unbalances the network 47 and develops a driving voltage having a magnitude proportional to the displacement of the door within 2 /2 degrees of its open position. i It has been determined from actual test that the operator 32 moves the door 34 from its closed to its 90 degree open position in 2.5 seconds. The door reaches the following open positions in the following total times: 2 /2 degree open position.3 of a second; 60- degree open positionl.2 seconds; and 90 degree position2.5 seconds. As indicated above, the motor control winding is deenergized for .3 of a second when the door reaches its 60 degree open position. Moreover, it has been found that thedoor is moved out of the path of a person walking through the entrance 20 quickly and dependably, and does not in any way interfere with or obstruct the person.

The door 34 is automatically closed by the person walking oif of the mat exit side 42b and opening the contacts 83, assuming of course that no one else is standing on the mat entrance side 42a. The opening of the contacts 83 opens the energization circuit for the safety relay 150 with the result that the contacts 152 are opened and the second energization circuit for the control relay 160 is opened. Since the first energization circuit controlled by the control relay 160 was opened by the opening of the contacts 142 incident to deenergization of the operate relay, the control relay 160 is deenergized. The deenergization of the control relay 160 causes the contacts 97a104a, contacts 164, and contacts 166 to open and the contacts 97a- 100a and contacts 162 to close. The closing of contacts 162 serially connects the door switch 174 with the damping winding 56 while the opening of the contacts 164 disconnects the door switch 170 from the damping winding, thereby to effect the immediate deenergization of the damping winding 56 as shown in FIG. ll. The movement of the contact wiper 97a from the contacts 104a to the contacts 100a causes the switch 97 to move from the voltage level 104- back to its original voltage level 100 thereby to effect an unbalance of the potentiometer network 47 to produce a voltage differential across the cent'er arm 96 and to develop a driving voltage for the motor control winding having such a phase as to move the door toward its closed position. Thus, the servomechanism now seeks its door closed null position. The driving voltage has an initially high magnitude for promptly moving the door, which magnitude is linearly decreased to a substantially constant value at an 87 /2 degree open position as the slider 99 is moved from its voltage level 106 to its voltage level 105 under the control of the follower 2O device 50. The door moves at an optimum closing speed from its 87 /2 degree position to its 30 degree open position.

As the door passes its 60 degree open position, the motor interrupting subcircuit 54 is reset. Specifically, the camming portion 180a of the cam 180 disengages the lever arm a, thereby to open the contacts 171 and close the contacts 172. The opening of the contacts 171 performs no useful function since the contacts 164 are open under the control of the control relay 160. The closure of the contacts 172 completes a circuit for the capacitor discharging current from the capacitor 200, the rectifier 196, the resistance 198, the contacts 172, and closed contacts 176 so that after the capacitor 200 is discharged the DC. voltage is supplied to both plates of the condenser 200.

When the door reaches its 30 degree open position, the camming portion a of the cam 180 engages the lever arm 174a thereby to effect the opening of the contacts 176 and the closure of the contacts 175. Again, both the damping sulbcircuit 52 and the motor interrupting subcircuit 54 are operated. In regard to the damping subcircuit 52, it is energized during the movement of the door from its 30 degree open to its closed position and thereafter as long as the door remains in its closed position, see FIG. 11. The closure of the contacts 175 completes the first energization circuit for the damping winding 56 from the terminal 144, conductor 181, resistor 182, conductor 183, contacts 175, socket 165, plug 167, a conductor 216, contacts 162, conductor 185, inductor 186, winding 56, power conductor 237, and ground. The energized damping winding produces within the space occupied by the rotor a stationary magnetic field which creates a resistive force to the rotation of the motor. Insofar as the motor interrupting circuit 54 is concerned, the opening of the contacts 176 causes charging current to flow from the terminal 144 through the winding a of the time pulse relay 190 into the condenser 2.00 so that the time pulse relay 190 is energized for approximately a three-tenths of a second time interval. opening of the contacts 192 to open circuit the motor control winding 48 for the three-tenths of a second time interval (see FIG. 10) during which the motor 44 is exclusively damped by the damping subcircuit 52 and also eifects the closure of the contacts 194 to complete the third energization circuit for the damping winding 56. The completion of the third energization circuit during the closing of the door performs an anti-guillotine function of protecting fingers against injury by inertia movement of the door through the doorway 22. Were it not for this third energization circuit, free inertia door movement would occur when the mat entrance contacts 81 are closed during the three-tenths of a second time interval since the first and second energization circuits would be opened. Specifically, the closure of the contacts 81 causes the control relay 160 to be operated thereby to disconnect the door switch 174 from the winding 56 by opening its contacts 162 and thereby open the first energization circuit and to serially connect the door switch 170 with the winding 56. However, at this 30 degree open position the contacts 171 of switch 170 are opened thereby to open the second energization circuit for the winding 56. Accordingly, no damping voltage is supplied to the damping winding 56 and no resistive force is applied on the motor; and because the energization circuit for the motor control winding 48 is opened, closing momentum of the door might cause the door to uncontrolla'bly swing through the doorway 26. A person having knowledge of the latching speed of the door 34 would not expect this free momentum movement of the door and may seriously injure his fingers or limbs between the door 34 and the jam": 24. To avoid this type of door operation, the damping winding 56 is thus energized by the third energization circuit independent of the first and second energizing circuits when the motor The energization of the relay 190 effects the 21 oontrolwinding 48 is deenergized during the three-tenths of a second time interval.

The door 34 travels at a reduced latching speed during movement of the oor from a few degrees less than the 30 degree open position to its door closed position since both the control winding 48 and the damping winding 56 are energized. As the door moves between its 2 /2 degree open position to its closed position, the magnitude of the driving voltage applied to the motor control winding 48 progressively decreases under the control of the follower device 50. Accordingly, the damping of the motor 44 becomes progressively less as the speed of the motor decreases. The door, however, is slightly underdamped so that it moves fairly quickly into its door closed position with only a slight overshoot.

It should be appreciated, of course, that in the event the mat entrance contacts 81 are closed at any time during the closing of the door, the operate relay 140 and the control relay 160 will be immediately energized thereby to unbalance the potentiometer network '47 and cause the mechanism to seek its door open null position. Accordingly, a driving voltage is applied to the motor control winding 48 having an opposite phase to the voltage applied during closing of the door, with the result that the motor reverses in direction and moves the door towards its open position.

The door is maintained in its closed position under the control of the servomechanism which holds its door closed null position. Similar to when the door is in its open position, the motor control winding 48 is deenergized and the damping winding 56 is energized (see FIGS. 10 and 11) as long as the door remains in its closed position and the system is turned on. If, for example, a sudden gust or draft moves the door of]? its closed position, the follower device 50 unbalances the potentiometer network 47 to provide a driving voltage having the necessary phase relative to the reference voltage winding 60 to move the door back to its closed position. It should be noted that the greater the displacement of the door from its open position, the greater is the magnitude of the driving voltage applied to the motor control winding. This result is achieved because of the configuration of the cam 110 which unhalances the network 47 and develops a driving voltage having a magnitude proportional to the displacement of the door within 2 /2 degrees of its closed position.

AUTOMATIC OPERATION-SAFETY OPERATION The electric door operator 34 is characterized by several safety features which practically eliminate the possibility of injury to persons walking through or moving adjacent to the entrance 2%.

1. Door ClsedPers0-n on Mat Exit Side In the event that a person steps onto the mat entrance side 42a when the door is in its closed position while another person is standing on the mat exit side 42b, the door does not open and will not open while the person remains standing on the mat exit side 42b. Accordingly, an inattentive individual standing on the mat exit side 42b is afforded protection against being struck by the moving door. Specifically and referring to FIG. 8, when the person first stands on the mat exit side 42b, the switch contacts 83 are closed thereby to energize the safety relay 150. The energization of the safety relay causes contacts 154 to be opened thereby to open the first energizing circuit, including the contacts 149 of the opcrate relay 140, for the control relay 160 and prevent the energization of the control relay 160. A person may walk on and off the mat entrance side 42a without opening the door and as long as the person stands on the mat exit side 42b the door remains closed. Of course, once the person steps off the mat exit side the safety relay 150 is deenergized and the contacts 154 are closed. If either a person is standing on the mat entrance side 42a or a person thereafter steps on the mat entrance side 42a, the

22 operate relay 140 is energized to complete the first energization circuit for the control relay 160 thereby to cause the servomechanism to seek its door open null position and open the door.

Although the electric door operator 32 does not automatically open the door 34 when someone is standing on the mat exit side 42b, the door 34 nevertheless may be manually opened by a person walking through the entrance 20. Accordingly, the entrance 2% is not rendered entirely inoperative and the door 34 is operated under the manual control and care of a person passing through the entrance 20.

2. Door Opened-Person 0n Mat Exit Side The door 34 remains in its open position as long as a person stands on the mat exit side 42b and holds the contacts 83 closed to complete the energization circuit for the safety relay 150. The energized safety relay 150 keeps the contacts 152 closed to complete the second energization circuit for the control relay 160, and the servomechanism holds its door open null position. Irrespective of persons walking on and off of the mat entrance side 42a, the servomechanism holds its door open null position and the door remains in its open position as long as the person remains standing on the mat exit side 42b.

"The door 34 also remains in its open position when persons alternately stand on the mat entrance side 4211: and the mat exit side 42b provided that the time lapse between the closure of the contacts 81 and 83 is less than quarter of a second time delay occasioned by the charge on the capacitor 173 discharging through the relay winding 160a. Hence, the control relay 160 is continuously energized even though there are short time intervals when both the mat contacts 81 and 83 are opened.

3. Door Cl0sing-Person ,on M at Exit Side In the event that the door 34 is being closed automatically under the control of the servomechanism and a person intentionally or inadventently stands on the mat exit side 42]), the door is immediately stopped thereby to prevent the person from being struck by the door moving at its full power. Specifically, during closing of the door all of the relays 140, 150* and 160 are deenergized and a driving voltage is supplied by the unbalanced network 47 to the control winding 48 as a result of the switch 97 being moved to the voltage level 100 incident to deenergization of the control relay 160. However, when a person stands on the mat exit side 42b during the closing of the door, the motor is simultaneously deenergized and damped to effect the immediate stopping of the door. Specifically, incident to closure of the mat exit contacts 83, a circuit is completed for energizing the safety relay which causes the closure of the contacts 152 and 158 and the opening of contacts 154 and 156. The opening of the contacts 156 opens the circuit between the end 96a of the arm 96 and the voltage level 100 on the winding 92, thereby open circuiting the center arm of the potentiometer network 47 and removing the driving voltage from the motor control winding 43. The closure of the contacts 158 completes a fourth energization circuit for the damping winding as follows: from the DC. terminal 144, the conductor 181, resistor 182, conductor 183, a conductor 218, contacts 158, conductor 220, conductor 216, contacts 162, conductor 185, inductor 186, damping winding 56, power conductor 237, and ground. Thus, the motor control winding 48 is deenergized and the motor damping winding 56 is simultaneously energized to cause the door .30 to instantaneously stop. Furthermore, the door remains in its stopped position intermediate the door open and closed position under the control of the safety relay 150' as long as the person remains on the mat exit side 42b. If while the person stands on the mat exit side 42b another person stands on the mat entrance side 42a to energize the operate relay 140, the door remains in its arrested position since the energization circuit,

23 including the operate relay contacts 149, is open circuited by the opening of the safety relay contacts 154. Accordingly, the door 34 does not move even though persons walk on and off the mat entrance side 42a.

When the person steps off of the mat exit side 42b, the contacts 83 are opened and the safety relay 150 is energized whereby the contacts 152 and 158 are opened while the contacts 154 and 156 are closed. The opening of the contacts 158 simultaneously opens the fourth energizing circuit for the motor damping winding 56 to remove the resistive and retarding force from the motor 44. The closure of the contacts 156 closes the previously opened circuit between the end 96a of the arm and the voltage level 160 of the winding 92 thereby applying a voltage differential across the center arm 96 of the potentiometer network 47 so that once again a driving voltage is applied to the motor control winding 48. With the motor 44 reenergized, the servomechanism again seeks its door closed null position and the door 34 is returned to its closed position under the control of the potentiometer network 47 and the follower device 50.

CLOSER OPERATION The electric door operator 32 may be manually conditioned to operate as a conventional double-acting door closer, i.e., to automatically return the door 34 to its closed position after the door is manually opened on either side of the doorway 22, by disconnecting the mat entrance and exit switches 81 and 83 from the treadle mat subcircuit 49 to render the control relay 160 ineffective. Hence, irrespective of actuation of the mat switches by a person walking through the entrance 20, the control relay 160 remains deenergized so that the switch 97 does not unbalance the potentiometer network 47. In this connection, a switch 222 is mounted in the jamb 24 of the doorway and is operable to open a pair of contacts 224 in the conductor 145. The opening of the contacts 224, thus, opens the energization circuits for both the operate relay 140 and safety relay 150 so that even though the mat switch contacts 81 and 83 are closed by a person standing on the mat 42 the control relay 160' remains deenergized. With the control relay 160 rendered ineffective, the switch 97 at the end 96a of the center arm 96 of the potentiometer network 47 remains at the voltage level 100 as a person walks through the entrance 20 with the result that the network 47 is not unbalanced by the switch 97. However, in response to the manual movement of the door '34 by a person walking through the entrance 20, the follower device 50 effects an unbalance in the network 47. Specifically, the cam 110 is rotated thereby to move the slider 99 from the voltage level 192 to another voltage level either toward the voltage level 101 if the door is opened on the right side of the doorway 22 or toward the voltage level 105 if the door is opened on the left side of the doorway 22. Thus, the slider 99, instead of the switch 97, effects an unbalance in the potentiometer network 47 and causes a driving voltage to be applied to the motor control winding 48 to urge the door towards its closed position.

It will be appreciated that a person manually opening the door must overcome the motor torque developed as a result of unbalancing the network 47 and must also overcome the resistive force offered by the energized damping winding 56. As described above, the motor damping winding 56 is energized when the door 34 is closed and ofiers a resistive force to the motor if the door 34 is moved away from its closed position. Accordingly, when the door 34 is manually opened on the left side of the doorway 22 as viewed in FIG. 1 (opening movement A in FIG. 9), the motor damping winding 56 remains energized to offer a resistive force directly proportional to the speed of the door opening movement (see FIG. 16). This result obtains since between the door closed and 30 degree open position the cam 180 maintains the contacts 175 closed to complete the first energization circuit for the damping winding 56. This first energizing circuit is not opened -by the contacts 162 as is normally the case when the door is automatically opened, since the control relay 160 is not energized by the treadle mat subcircuit 49. As the door reaches its 30 degree open position, the cam 180 disengages the switch 174 to effect the closure of the contacts 176 and the opening of the contacts 175 with the result that the first energization circuit is open. circuited and the motor damping winding 56 is deenergized (see FIG. 16). From the 30 degree door open po' sition to degree door open position, the motor damp+ ing winding 56 is deenergized and no damping resistive: force opposes the manual door opening force.

The magnitude of the driving voltage supplied to the motor control winding 48, the switch voltage 97 and the slider voltage 99, as the door is manually opened 80 degrees and automatically closed on the right side of the doorway 22, is illustrated in FIG. 15. During initial opening movement of the door 34, the cam 110 rotates counterclockwise and the follower pin 114 moves along the groove portion 132 thereby to displace the follower bar 116 and move the slider 99 from the voltage level 102 toward the voltage level 105. The movement of the slider 99 effects an unbalance of the potentiometer network 47 thereby to produce in the motor control winding 48 a driving voltage having such a phase as to urge the motor to return the door to its closed position. When the door reaches its 2 /2 degree open position, the follower pin 114 moves into the groove portion 133 and the slider 99 reaches the voltage level 105. The slider remains at the voltage level 105 until the door 34 reaches the 87 /2 degree open position where the follower pin 114 moves into the groove path 134 and the slider 99 moves from the voltage level 105 toward the voltage level 106, the driving voltage being proportional to the difference between the switch and the slider voltages.

In normal usage, a person manually pushes the doorautomatically close the door (closing movement B in FIG. 9). Actually, the servomechanism now seeks its door closed null position. The driving voltage as shown in FIG. 15 remains at a value proportional to the difference between the switch 97 and the slider 99 voltages, i.e., voltage level 100 and voltage level 105, during closing of the door from its 80 degree open to 30* degree open position and effects an optimum door closing speed. When the door 34 reaches its 30 degree open position, the motor interrupting subcircuit 54 and the damping subcircuit 52 are operated such that the motor control winding 48 is temporarily interrupted for a predetermined time interval (see FIG. 15) and the damping winding 56' is en ergized during the last 30 degree travel of the door (see FIG. 16). Thus, the speed of the door is changed from an optimum closing speed to a slow latching speed in exactly the identical manner as described above in connection with the automatic operation of the door.

In the event that the door is manually opened on the right side of the doorway 22 as viewed in FIG. 1 (opening movement C in FIG. 9), both a damping resistive force and an opposing motor force act in opposition to the manual opening force. Specifically, the earn ro tates in a clockwise direction to cause the follower pin 114 to travel in the groove portion 131 and to move the slider 99 from the voltage level 102 toward voltage level 101. After the door is opened 2 /2 degrees the follower pin 114 moves into the groove portion and the slider 99 reaches the voltage level 101. Thereafter the slider 99 remains at the voltage level 101 and the switch 97 remains at voltage level 100 as the door opens to its 90 degree open position so that a constant driving voltage is supplied to the control winding 48 (see FIG. 15 The resultant driving voltage 48 is of opposite phase to the driving voltage obtained during opening movement of the door on the left side of the door-way 22 and urges the door to return to its closed position. In addition to the opposing motor force, the damping resistive force is applied to the motor 44 during the first 30 degree opening move: ment of the door (see FIG. 16). Similar to the door opening on the right side of the doorway 22, the motor damping winding 56 remains energized until the door reaches its 30 degree open position wherein the 60 degree peripheral cam portion 180a of the earn 184 disengages the switch 174 thereby to open the first energizing circuit for the motor damping winding 56. Accordingly, from the 30 degree position to its 90 degree open position, the only force acting in opposition to the manual door opening force is the opposing force of the motor.

After the door is manually moved to its maximum open position, for example, an 80 degree open position, it is released whereupon the driving voltage becomes effective to automatically return the door to its closed position (clos ing movement D in FIG. 9). During closing movement, the servomechanism seeks its door closed null position. The magnitude of the driving voltage between the 80 degree and 30 degree open position as illustrated in FIG. 15 is constant and is proportional to the difference between the slider 99 and switch 97 voltages, i.e., voltage level 100.

and voltage level 101, thereby providing an optimum closing speed for the door. As the door reaches its 30 degree open position during its closing movement, the motor interrupting subcircuit 54 and the damping sub-. circuit 52 are operated with the result that the motor control winding 48 is temporarily interrupted (see FIG. 15) and the damping winding is energized during the last 30 degrees of door travel and as long as the door remains in its closed position (see FIG. 16). Accordingly, the door speed changes from its optimum closing speed to its latching speed in the same manner as described above in connection with automatic operation of the door.

HOLD OPEN OPERATION It is often desirable to have the door 34 remain in a continuously open position, for example, when deliveries are being made, or when it is desired to ventilate the interior of the building. The electric door operator 32 is adapted to be conditioned to hold the door in its open position with the use of no more power than is required to hold the door in its door closed position. To this end, a hold open switch 226 is mounted in the jamb 24 and is manually operable to close a pair of contacts 228 for completing a second energization circuit for the operate relay 140 as follows: from ground, a conductor 230*, contacts 228, a conductor 232, the conductor 146, the winding 140a, conductor 1147, the 12 volt A.C. source 143, the conductor 148, and to ground. It will be observed that the circuit comprising conductor 230, the contacts 228, and the conductor 232 is in parallel with the mat entrance contacts 81 so that when the contacts 228 are manually closed, the operate relay 140 is energized irrespective of the opened mat entrance contacts 81. The energized operate relay 140 effects the energization of the control relay 160 with the result that the servomechanism seeks its door open null position and the door is opened in the same manner as when a person steps on the mat entrance side 42a. The servomechanism holds its door open null position and retains the door in its open position as long as the switch contacts 228 are closed. If a force, e.g., a force resulting from wind gusts, children, animals or the like, moves the door from its open position, the potentiometer network 47 becomes unbalanced and develops a driving voltage which has the proper phase to return the door to its open position, in the same manner as described above. It will be appreciated that even though the mat entrance contacts 81 and the mat exit contacts 83 are closed and opened during the movement of traflic through the doorway 22, the door remains closed under the direct control of the operate relay 140 and the control relay 160'.

If it is desired to condition the electric door operator for automatic operation, the switch contacts 228 are opened to cause the deenergization of the operate relay and the control relay 160 with the result that the servomechanism seeks its door closed null position and returns the door to its closed position as described above.

PANIC OPERATION The entrance 20 accommodates single lane trafiic moving into a building, i.e., from the right side to the left side of the doorway 22 and, to this end, the operator 32 is set to automatically open and close the door 34 on the left side of the doorway 22. In order to permit people to pass out of the building, i.e., from the left to the right side of the doorway 22, during an emergency, for example, a fire or the like, it is extremely important that the people may panic or manually open the door on the right side of the doorway 22 without any interference from the electric door operator. Moreover, it is preferable that the door he panic opened without breaking any door positioning means or without requiring any panic device to be reset or readjusted by a Serviceman or the like. In accordance with a feature of the present invention, the electric door operator 32 is so designed that it permits panic or manual opening of the door and then automatically returns the door to its closed position under the control of the servomechanism,

More specifically, assuming the door 34 is closed and a person starts to walk through the entrance in a direction opposite to the normal flow of traffic, he first steps on the mat exit side 42b to close the witch contacts 83. The closure of the contacts 83 eifects the energization of the safety relay with the attendant opening of the contacts 154 and 156. The opening of the contacts 154 open circuits the first energization circuit for the control relay thereby assuring that the switch 97 remains at the voltage level 100. The opening of the contacts 156 opens the circuit between the end 96:: of the center arm 96 and the winding 92, thereby to assure that no' driving voltage is supplied to the motor control winding 48 while a person stands on the mat exit side 42b. As the person passes through the entrance 20, be manually opens the door on the right side of the doorway 22 (opening movement C in FIG. 9). After 1%. or 2 degrees of opening movement, a panic safety switch 240 (see FIGS. 2, 8 and 17) is opened to open circuit the energization circuit for the operate relay 140 and hence to render the control relay 160 inoperative, as described below. The panic door opening movement also causes the cam 119 to rotate clockwise to move the follower pin 114 into the groove portion 131 and to move the slider 99 from the voltage level 102 toward the voltage level 101. When the door reaches its 2 /2 degree open position, the follower pin 114 reaches the groove portion 130 and the slider 99 moves to the voltage level 101 where it remains during the balance of the door opening movement. Although the slider 99 and switch 97 are at different voltage levels and the potentiometer network 47 is. unbalanced, no driving voltage is supplied to the motor control winding 48 since the center arm 96 of the network 47 is open circuited by the opened contacts 156. The magnitudes of the driving voltage, slider voltage and switch voltage are illustrated in FIG. 13 as the door is panic opened to an 80 degree open position and automatically returned to its closed position.

It should be realized that since the cam portion a of the cam 18% engages the switch 174 the damping winding 56 remains energized throughout the first 30 degree opening movement of the door so that a resistive damping force proportional to the manual speed of the door is applied to the motor 44 (see FIG. 14). The panic operation differs from the closer operation in that during the closer operation both a damping resistive force and rota tive motor force oppose the manual opening force while in the panic operation only the damping resistive force 

